A reactor is a circuit component that increases or reduces a voltage. For example, a type of reactor that is used for a converter mounted on a vehicle such as a hybrid vehicle includes an annular (O-shaped) magnetic core and a pair of coils that are formed by winding a wire and arranged in parallel with each other.
PTL 1 discloses another type of reactor including a magnetic core that has an E-shaped cross section, which is a so-called pot-shaped core. The magnetic core includes a solid-cylindrical internal core portion that is disposed inside a coil, a hollow-cylindrical core portion that is disposed so as to surround the outer periphery of the coil, and a pair of disk-shaped core portions that are disposed on both end surfaces of the coil (see FIG. 1 of PTL 1). In the pot-shaped core, the internal core portion and the cylindrical core portion, which are concentrically disposed, are coupled to each other by the disk-shaped core portions, and a closed magnetic path is formed. Moreover, PTL 1 discloses that the cross-sectional area of the internal core portion can be reduced by making the saturation magnetic flux density of the internal core portion be higher than those of the hollow-cylindrical core portion and the disk-shaped core portions, and thereby a small reactor can be obtained.